1. Field of the Invention
The present invention relates to wireless networks and, more particularly, to a method and system for multicasting messages to wireless terminals in such networks.
2. Description of Related Art
In a typical cellular wireless network, a geographic area is divided into cell sectors. Each cell sector defines a geographic area in which wireless terminals (such as cellular telephones, personal digital assistants (PDAs) and/or other devices) operate. The wireless network normally has a base transceiver station (BTS) assigned to one or more cell sectors. The BTS produces a radio frequency (RF) radiation pattern over the one or more cell sectors. The RF radiation pattern allows the wireless terminals located in the one or more cell sectors to exchange signals with the BTS over an air interface.
The wireless network typically has a plurality of BTSs. The plurality of BTSs communicates concurrently with a base station controller (BSC) that aggregates signals received from the plurality of BTSs. The plurality of BTSs and the BSC is commonly referred to as a base station. And the wireless network may have a plurality of base stations. The plurality of base stations in the wireless network is referred to as a base station system (BSS).
Each BSC in the wireless network may communicate with a packet gateway and a mobile switching center (MSC). The packet gateway and the MSC function to set up and connect calls with other entities. For example, the packet gateway may set up and connect calls with a server or other entity on an Internet protocol (IP) network, and the MSC may set up and connect calls with a telephone on a public switched telephone network (PSTN).
Generally, the BSC will assign a traffic channel to each wireless terminal for transmitting and receiving signals over the air interface. Additionally, the packet gateway establishes a radio-packet (R-P) link with the BSC. The R-P link carries signals between the packet gateway and the BSC. The packet gateway establishes a separate R-P link for each wireless terminal in the wireless network, and in this regard, the signals carried by each R-P link are associated with a particular wireless terminal. The R-P link is referred to as the A10/A11 link in the code division multiple access (CDMA) network architecture.
In some instances, a server in the wireless network may send information to wireless terminals in the wireless network. The information may be of interest to users of the wireless terminals. For example, the information might be sports scores, weather reports, and advertising messages. The server may insert the information into a message and send the message to one or more wireless terminals.
In order to facilitate convenient distribution of a given message to multiple wireless terminals, the packet gateway may maintain a list of wireless terminals authorized to receive a copy of the message. A single copy of the message may then be sent to the packet gateway, and the packet gateway may determine from its list which wireless terminals are authorized to receive a copy of the message. The packet gateway may then transmit a copy of the message respectively to each such wireless terminal, via the wireless terminal's respective R-P link (to the BSS, which then transmits the message to the wireless terminal). In this way, the wireless network is able to send the message to multiple wireless terminals in response to just one copy of the message being sent to the packet gateway.